Underreamer



Sgt-21 1 25. 1,600,783

w. E. YOULE UNDERREAMER.

' Filed Oct. 2, 1922. 4 Sheets-Sheet 1 IN VEN TOR.

g mlzizmlfyauifi Patented Sept. 21,1926.-

-' i V I 1,6tt,783

WILLIAM YOUl'i E, 0F LOSANGELES, CALIFORNIA.

UNDERREAMER.

Application filed October 2,

This inventionrelates to underreamers for reaming well-holes below thewell casout overloading any one part of the tool.

One of the major objects of this invention resides in the provision ofanew type of underreamer characterized by having one reaming cutter orbit slidable inthe body relative to the opposed cutter and in 'anarcuate path, the-opposed cutter being approximately stationary as tolongitudinal translation .and supported to tilt in av collapsingoperation under control of the slid-V ing cutter.

Another object is to provide for a quick immediate release of thecutters when stuck in the well bore, such release being accomplishedwithout disengagement of the dovetails of the cutter shanks from fullcontact against the outthrust surfaces of the companion dove-tail waysin the body, such full contact maintaining during the whip of the toolin a reaming operation.

Another object is to provide an underreamer .in which all possibility oflosing the cutters in the well-bore-is eliminated, the parts being soproportioned and ar ranged that in case the supporting means of eithercutter be broken the other cutter will hold the broken cutter againstloss from the body.-

A further objectis to provide an underreamerhaving one-tilting and onesliding cutter each provided with dove-tailshanks engaging'companiondove-tail ways ill the body, and in which neither cutter shank hasapivotal action on outthrust surfaces of the ways. r

Another object resides in the provision of a spring actuated rod forsupporting the sliding cutter, with intermediate connections betweentherod and cutter compensating for the arcuate movement of said cutter.

, i another object is to provide a spring and position.

1922. Serial N0. 591,745.

rodcontainer removable laterally from the body as a self-contained unit,and inwhich the spring may be maintainedunder tension during removal-ofsaid unit.

A further object resides in providing an underrea m'er in whichin-thrusts are trans mitted directly from onecu-ttcr to the otherbearingsurfaces are arranged to relieve the cutter shanks and dove-tailsof excessive strains. i

ing and arrangement of parts by. which it below the body, and inwhichthe up-thrust i is possible to provide largedovetails'well ii set intothe body, cutter shanks of exceptionally large cross-sectional area,exceptionally large and direct up thrust bearingsurfaces,-'anon-removable support forthe tilting cutter which will not prevent aremoval of said cutter, cooperation between the two cutters which willpositively insure their expansion, exclusion of such dirtor foreignmatter aswould interfere with free i functioning of the parts and causeexcessive wear, and to provide a one piece body. in

which all the recessesare exposed and easilycleaned when the cutters areremoved;

A further object. resides in' the manner ofremoving the cuttersby amanipulation which bore. V

Various other objects and advantages will could not possibly occur in awellbe more fully apparent from the following description of theaccompanying drawings which form a part of th s disclosure, and

which illustrate a preferred form? ofenibodiment of the invention.

Of the drawings:

Figure 1 is an elevation-of my improved underreamer, the cutters beingin expanded position.

. Fig, 2 is a similar elevation of the lower portion ofthe underreamer,the cutters being in collapsed position. Fig. 3 is an enlarged bottom Ilan view of Fig. 1. I

F ig.: 4 isan enlarged bottom plan viewof Fig. 2.

Fig. 5 is a central vertical section showing the cutters in collapsedposition.

Fig. 6 is a vertical sectionon line 66 of Fig. 10, showing the cuttersin expanded Fig. 7 is ,a section similar to 6, sl1ow- 65 'Another objectresides in" the proportiontion of the underreamer looking at the left;,

ing the cutters in partially collapsed or in release position.

Fig. 8 isfla detailelevation illustrating the .manner of removing thespring container spring rod from the lips 22 which engage behind angledabutrnent surfaces 23 on the body to hold the ,lower-endof the springcarrier in place and for disconnection of the sliding cutter.

Fig. 9 IS an elevation of the lower posihand side of Fig. 1.

F 10 is an elevation looking at the right-hand side ofFig. l.

13-13 otFieg 6.

[ Fig.5 11 is -a central yerticalsection of, lower; 1 portion ofthelbpdy, F g-1 12 s n. enla ge b Qm P lNieW of the body.

'F'igg13 is an the n arged ,section 01 line 7 Figqlit is; an @margedflsgctibng Oh line .4=.,O,Fig..5;

Fin". 16" is an enlargedeperspective view.

C u I" I r of the iltmgteatter, ands-.1 a HFig. 117 is a enlargedperspective view of the sl idingfclltterq In th ad wln 's '1 n 5 I a 7 IA or the .underreamernhav ngthe :usual tapered pin 2, forattachment tothe tool string, and provided-at itslower end ,with opposed. Iopenslipwaysg andlttzoereceivethe shanks r of the cutter-s.Thesside-cwallsof the respec; v tive slipflwaysiaregroovedtongproviderdove tail waysfijandfi,the'guideways.oidefiningttention is directed to the several views, and; ,t

outthrust hearing;surfaces] which, are londiate webte9 providesianabutment or; seat which supports the tilting, cutter and the ripper,wall ll' 'of thersli-pzway 3 provides an f inwardly and upwardly angledtip-thrust surface; which will belengagecl by the upper end of-the shankof; the tiltingv cutter as Willi later .be HeXplained The vlower vendofthe body-1 provides transverse up-t'hrust hearing faces .orsurfaceslQ. and 13 :on each USlClQ of the respective slip-ways theseup-thrustsurfaces being preferably anglednor inclined inwardly andupwardly towards each other." h se 521965512- andul3e preferably-c0nsti.-' tute the extreme lower end faces of the body.

The side Walls of thebodyabovethe slip way 5t is longitudinally.groovedfltol provide a. spring chamber 1 5 \vhich;.cornmunicates Qwithvsaid slip-way,-:,the side wallsofsaid chance her being in plane with thebase of the dove tail ways, 6 so as toattordxaneasy machining of saidways and said chamber.

The-spring charnherv15 is adapted: to :recelve aself-contained.springrod unitcoinprising a cover plate oruspringcontainer 16 having. an inwardly. extending lateral. lug

pro'vided'with a vertical bore 18 through; V '19, andpiyotallyiconnected-ttheretojoy aa'pin which spring rod: 19 extends anda spring the groove125 when; the plate {is in. placeo j.

vertical sectionhon, line designates, the body. I

.sertedi a suitable tool to pry the pl ateiloose.

, fore does 7 not requirel -any. screw-threaded;

lshank fil, the upper end of whicha-isaiangled. to the same, degree-as sthe ,upper -.wall1.

sinwardly extending pintle:nose: .or :pivot engagement upon theabutment- 01 seat- 1t) an upwardly extending shank 37 having its;

the free end of the lateral lug 17, engages. into a recess 2a in thebody, so that thee75 strains occasioned by the tension of the springwill. he transmitted: directly; to tllBz M body. The upper Wallofthechamber 115, is.

angled inwardlyand downwardly; anclhas'a f centraLgroove-25, anclthe.,upper.lend ofv'ethe $5M platelllfi is correspondingly angledqandusvprovided with a lug 26 adapted to ineshiinto The plate :16 is isecuredinplacesby aJbQlUQ-Z. which extends laterally through aligned 'ap erturesin the body and win the lug .26; with v the bolt; retained in place by.a splitv cotter;

pin 28, (see Fig.-10).- To facilitatelatre inoval of the cplatera't'terthe boltthastheeni. retracted, arecess'29 is providedatithe up- .20; perend ofv the lug 26 intowhiclrmayabe in:-

a The above described or anization of.) art t a b l provides/a one.plecebody havlng nocentlail i ly bored spring 'chambe rnandswhichthere,

jointsor sub-connections. 3 7

Describing thereamingeuttersiorcblts aa :particularly to Figs. 16 and17. Thentilt- 2 9) ing cutter-30 has an upwar.dly-. extendin oftheslip-sway .3, and isvprovidedvwith an projection "32 which has a..slidingpivotalt on' the web 9 ofr the loody fOn opposite sides oftheshanlr3l, the body-loft the cut-. l ter 30' extends laterally toform-,up-thrtist bearing surfat'es 33 angled for icooper-a' tiveengagement with the transverse tip-thrust bearing surfaces 12 of thebody-. when'Tthe cutters are in expandedposition. v- Dove-tail. i

ribs 34 extend outwardly'fromthe side w-allsv- .oif the shankSL-andwheiwthe cutterwis' in "position in the slip-way 3, thesedove-tails; sl dably :engageain the dovevtail ways 5,,

their outer edges -35v providing outthrustpw bearingsurfaces forengagement.withithe :29

. 'out-thrust .hearingisurfaces 'Z-formed-by said m .ways. a

The :sliding reaming cutterror :bit- 3 6;ha's g 1.

upperrendibifurcatedto lGCQlVQuiJllB lower.x

end of a link .38to :which it is pivotally .con-

l nected by a'pin 39., the upper endiofcsaidr1m :linkextendingbetweenthe arms of aiforkedv 1 'head 40 on the lower end of thespring rod 41. On opposite sides of the shank 37, the body oftlie'cutter 36 extends laterally'to form up-thrust bearing surfaces 42angled these dove-tails slidably engage in the. dove tail ways 6, theirouter edges 44 providing arcuate' out-thrust bearing surfaces which arelongitudinally curved correspondingly to the arcuate out-thrustbearingsurfaces 8 formed bythe companion dove-tail ways 6;

The opposed transverse surfaces'of the bodies of the two cutters areformed to iii-.

' termesh when the cutters are in collapsed position, as shown in Fig.5. l/Vhen the cutters are in such collapsed position a latch shoulder 45onthe cutter 36 engages beneath a companion latch shoulder 46 onthecutter 30, and as these shoulders are approximately horizontal when thecutters are collapsed, the cutters will remain collapsed until thereamer is jarred, whereupon the tilting cutter 30 willswing away fromthe sliding cutter 36 under the influence of gravity and permit anupward movement of the sliding cutter under the influence of the springto expand the cutters. 7

Upon such release of the cutters and during the upward travel of thesliding cutter, the corner 47 of the cutter 36 will ride upwardly on thetransverse expanding surface 48 of the cutter 30 to initially expand thecutters, and then the surface or'abutment shoulder 49 of the cutter 36will engage the surface or abutment'shoulder 50 of the cutter 30"andcomplete the expanding 0f the cutters.

The surface 49 is of the same curvature as are the arcuate dove-tails 43and-the surface 50 of the cutter 30 is correspondingly curved so thatduring any downward movement of the sliding cutter 36 from its expandedpo-' sition and while the surfaces 49 and 50 are in engagement, thedove-tails of both out ters will remain in engagement with the outthrustbearing surfaces 7 and 8 of the ref said cutter together with thearcuate surspective dove-tail ways. a 7

When the cutters are in expanded posi-. tion, as shown in Fig. 6, thesurfaces 49 and 50 further serve as in-thrust bearing surfaces, theircooperative engagement transniitti'ng in-thrusts directly from onecutter to the other below the body, thereby reliev ing the cutter shanksand their dove-tails of a large portion of the strains caused by suchiii-thrusts, which are usually due to glancing blows-of the cuttersagainst the walls of the well bore. In instances where the cuttersbecome stuck in a well bore it becomes necessary to partly collapse thecutters soas to release the cutters. 'This is accomplished by pulli ingupwardly on the body of the underrsamer, causing a longitudinal slidingmovement of the arcuate surfaces 49'and 5O relative to each other andaninitial collapsing of the two cutters. ture of the arcuate dove-tails 43of the sliding cutter this initial collapsing or release of the cuttersis accomplished withoutwithdrawing the dove-tailsof the respectivecutters away from their full contact'with the out-thrustbearingsurfacesof the dove-tail ways, therefore, I provide for a quickrelease of the cutters-without any slapping 0f the dove-tails in theirrespective Ways. This is an important consideration as in many types ofuiiderreamers such slapping:

lease of the cutters and during the whip of the drill cable, constitutesone of the ma-' ]or causes for crystallization of the cutter shanks andthe ripping out of the dove-tailsfrom the body. 1

tsit is desirable to provide a positive tilt ing of the cutter 30 tocollapsed position, the

upper 'end of the sliding cutter shank provided with a cam shoulder 51which dur'-- 5 7 ing thedownward movement of the'sliding cutter, isadapted to engage the end of the 1 nose 32 ofthe tilting cutter, (see.Fig. v7)

and positively swing said cutter to the collapsed position shown in. 5.

The underreamer of the resent invention is also constructed so astoprevent loss of the cutters in the well bore and contribut- By reasonof the curva- 'of the cutters in their slipways during a rev I ing tothis object, the cuttersare provided with shoulders 52 and 53 which maybe considered abutment shoulders; they are adapted to interlock when thecutters are in collapsed position. p In considering'the possibility. ofbreakage of parts, it will be quite evident that the Ycross-sectionalarea ,ofxthe supporting nose; 32 ofthe tilting cutter isof such dimensions that breakage thereofis a remote possibility.

However, if this nose 32 should become brokenoff, the cutter 30 will notdrop from 1:

the body" when in expanded position, by

reason of the fact that the longitudinally angled dove-tails anddove-tail ways of faces 49-50 form, in eifect,a wedge preventing adropping of the cutter v3O so long as'even a relatively short portion ofthe dove-tails 34 remain in the companion ways 5, and. when the cuttersare in collapsed position the. engagement of the latch shoulder 46 onthe latch shoulder 45 will hold the cutter 30 from dropping. It istherefore. evident that even though a major portion ofthe shank .31should be broken off, the

provision of a self contained spring rod unit removable laterally,permits a one piece body in which the sp 'ing chamber is aligned withone of the open slipways and can be easily machined, j a H In a four andone-half .inch underreamer the arcuate dovetails permit a transverserelease of three-eighths of an inch witha down pull of only threequarters of an inch. 7 This small movement of the sliding cutter duringreaming means less wear, less shock, less crystallization and lessstrain on the bolt and spring. e Furthermore this movement is'so slightthat nothing large enough to do damage can get between the up-thrustbearing surfaces. At all times during reaming, thesliding cutter ofafour. and one-half inch underreamer has a fullbearing over four inchesin length on its dove-tails. V I

The tilting cutter is held inthe body by its heavy lug or, nose whichengages the web between the slip-ways. The lug extends across the entireface of the cutter shank and locks into the body without the use of keysor pins. Even should the lugshear, this cutter cannot drop from the bodyas long as the other cutter is present. The cooperat ing arcuateinthrust bearingsurfaces of the cutters extend the full width ofthe-cutters and insure an even action against a glancing blow on eithercutter.

The collapsing action of the cutters is made positive by the camshoulderon the sliding cutter engaging the supporting nose of the tiltingcutter, and this positive action also insures the cooperation of the twosafety interlocking shoulders on thecutters.

I From an inspection of the drawings, the. simplicity and strength ofthe body'con struction will be apparent, a continuous slot serving forboth the sliding cutter and'the' spring, and the side walls of thespring chamber are solidly braced against crushing, by the springcontainer." i /ith theoperat ing partsremoved all the slipways andresated for by building up this arcuate bearing surface.

cesses in the body are exposed and areeasily cleanable. This method ofmounting the. springand spring rod-makes possible the elimination ofadrilled spring chamber in the body, and obviates the necessity ofajointed body. The body and cutters-have-been so designed as to reducewear to a ininimumand the movement of the sliding cutter in reaming isso small that its wearing effect will be negligible. The tilting cutter,which in reamingdoes not move in the body, can wear at only one point,the broad arcuate inthrust bearing surface below the body. lVca-r atthis point can easily be. compen- Furthermore as the 'arcuate surfacesand dovetails wear evenly,-'these may be bu lt uniform curvature bowedup, and refinished to take up. for wear, without any work on the body.

While the specific form. of construction herein illustrated anddescribed providesa tool fully capable of fulfilling all of the ob-.jects primarily stated, it is to be understood that I donot wish tolimit the invention to the one formof embodiment disclosed,'for

having a longitudinallydisposed arcuate slipway uniformly curvedupwardly and outwardly from thesaid upthrust bearing surface, theuniform curvature enabling the same to guidea cutter to slide inan are.

-23. An unde'rreamer' body having an up- ;thrust bearing surfaceconstituting the extreme lower end face of the body and having a.dovetailed guideway capable of guiding a cutter to slide in anarclongitudinally disposed in the body and extending up wardly from thesaid up-thrust bearing surface and having arcuateout-thrust bearingsurfaces uniformly curved upwardly and outwardly. I

l. An underreamer body having an upthrust' bearing surface constitutingthe extreme lower end face of the body and having a dovetail guidewayfor, guiding a cutter to slide in an arc longitudinally disposed andextending upwardly from said upthrust. bearing surface,: said gu deway'hav ing: arcuate out-thrust bearing surfaces of middle portions.

outwardlylat their 5. An underreamer; body having I anl upthrust bearingsurface; constituting the ex-:

treme lower end faceof the body and having :two opposed longitudinally 1disposed guideways extending upwardly from said I bearing surface, oneof said guidewayshaving straight out-thrust bearing surfaces and theother having arcuate out thrust bearing surfaces of uniform curvaturecapable of guidinga cutter to slide in an'arc. f

6, An under'reamer body having an upthrust bearin surface on its lowerend, and

two opposed longitudinally disposed open slip-ways extending upwardlyfrom its lower surface, .and an intermediate web havmg means tocooperate with one of the cutters to supportthesame, one-slip-waydefining straight out-thrust bearing surfaces and the other defininguniformly curved nrcuate body having arouate-g guideways receiving ewith faces clonstituting out-thrust bearing -out thru'stbearing.surfaces,*and constitut move;thersame up and-dovvn inthe-'underj ing a guidewa'y for guiding a- -eutter to reamer body.

lide inan' arc. r 12. In an uniderreamer, the comb nation 7:'Anu-nderream'e'r bodyhaving an upof anhnderreanier body, a cutter having a'5 thrust-bearingsurface on its lower end, and body-portion. providedWith a1cuate e2; tvvo opposed ;longitudinally disposed open panelingsurface on its'i-nner face and pro- "slip-Ways --extending' --upwardlyfrom its vided With a shank having means for sup; 7 lower surface,-oneslip-Way defining straight -porting-the cutter extending upwardlytrom out-thrustbearing surfaces"longitudinally said body portion'andhaving longitudinally angled upwardly and outwardly and the disposed,-arcuate, dovetail ribsextendmg other slip-Way defining longitudinallydis'- from itsyside' faces, said-underreamer body posed arcuate0utthrust bearin-gsurfaces of having' -arcuate guidevvaysreceiving theunifornr-curvature;constitutinga guidevvay dovetail ribs, and meansco'operating'with ffor guiding-a 'cntter to slide in an arc.'---.-the'eutterto movethesame up or-down in 5 8. In an underreanier',thecombination of theguideways. V v

body *havingagroove in itsside -Wall eX- 1"; 13. Inanunde'rreamer; thecombination --tending-upWardly1 from its lower-* Surface, of anunderreamerbody, a-cutter having a the lower portionofsaid-groove-torming an; body-' iportiomprovided 'With. latchingopenaslip wvay and-"th 9," upperportiont-here o'faiforming-ga sprin g'chanaberya spring loshoulder and with anarcuate expanding I surface onits inner side, said cutterhaving cated in thespring-:eham-ber,theWvalls of the] lower -portionot-the groovevybeingdovetail shankextending upwardly from the body-portion, andhaving an abutment formedto provide arcuate,outrthrust-bear --shoulder onthebodyportion, and acomi g rfa cut gui-ded iIi p y-mpanion cut-ter'having an. abutmentsl'ioulder 'and==cooperatingwith the spring, and a re}, movable coverfor the spring chamber. 9. An underrea-mer body having tWo op andtoi.;eng age the first named abutment P P fi P y extending np ard y"shoulder and cooperatekwith the same to v from itsve xtreme 'lower en'dfa-cewith said hold the cutters in an expanded relation.

face on opposite sides ofthe slip ways pro- 14; 1 An d am having a'body, a vidingi oppositeup-thrust-bjearingsurfaces-reamingcutter'tiltingly' supported in theangled-upwardly ancl inward y towards'each lower end of the body, andalongitudinally 'f-Ot e one' 'slip-zwa y having its-.top Wall'movable-reaming outter'mounted and posi- =ang1ed r y p ar y S tivel'yguided in'thebody in an arcuate'pz'ith, p WELllS 1' undercut t0 PIOVlClG'WSJYS the tworcuttrs a ooperative ut-fey defining out-thrust bearingsurf-aces; and expan'ding--engagefnent v h ip y e g d rc p vi I 15.An"uIiderreamer "having a body, a e -'1 W g 511961121118 Out-thrust.spring flCttlttQd'fIOflSlldiLbl in the "body, a bearing surfaces ofuniform curvature, 'oonl i it di' fl mgvablg reaming, utter 40""Stitutingguidewayslto guide Wcutter inim; 'IlGCtBClWltll said rodandmounted and posi- O- p 7 tively guided in the body in an arcuate'path, In an l rr fl ma and a second. reaming cutter tiltinglv supi of abody,- a cutter liaving abody-portion and 'a shank extending upwardlytherefrom- 5 having means for supporting thecutter, "said shank providedwith longitudinally' dis posed, areuate dovetail ribs" extending froirrits-oppositeside Walls, the-said underreamer rod and'oooperating withthe slidable cutter in acutter expanding operation,

16; An .underreamer. having a a j body, a spring actuated rod slidabl'ein'the body, a longitudinally movable reaming cutter cennectedwithsaidrod'and slidable in the body in an arcuate path, and asecond reamingcutter tiltingly supported in the body independently of said rod, saidcu ters ha: A ing-inner' surfaces cooperating to, cause the the-dovetail-ribs' and guidingthe ;cutter, T i and-means'for controllingthe cutter'to-Tnove -thejs'ame up or jdown in-thefgnideways. I

L a 11 In an 'unde-rreamer,"thesc'ombination k of; an un'derreamer-body,'a cutter having a body-portionflend ashank extending up;

ardl therefrom having means 7 for sup porting the cuttergsaid shankhaving up j' e'af g.urfaceson eitherside of the, the'sliding cutter,effects a positive'collnpsishanl'rysaid shank-also'having dovetailed'ribs. ing movement of the tilting cutter.

i 17. An underreamer having a body, a longitudinally immovable cutterpivoted in the'body totilt transversely, a second cutter to permit saidcutters t0v collapse when in another pos tion, and other cooperatingsurfaces, the bodyo'f the cutter below the shank having an arcuateexpanding surface on its nner face, said; underreamer body. having maticmean'si adapted to 'tr'ansiate said to cooperate -:With the latchingshoulder i when the cutters are in a collapsed posit-ion,

'cutters to expand When in oneposition, and

"faces whereby a collapsing movement of ported in the body independentlyof said i p V V longitudinally slidable in the'body and posiarcuateguide ivays for receiving said r1bs,-t1vely guided'in an arcuate path,'andautoefifand means cooperating with the cutter to 33$ 0nd cutter,said cutters being free-ofeach. other and normally held expanded bysaid' means operating the second cutter.

18.' An underreamer having a body, a cutter pivoted in the body to tilttransversely, a second cutter longitudinally slidable in the body andpositively guided in an arcuate path, and automatic means con- 'nectedto said second cutter and functioning to elevate said second cutter, thecutters being free of each other and expanding upon the upward movementofsaid second cutter. V

19. An underreamer having abody, a

longitudinally immovable cutter pivot-ally supportedon the body totilttransversely, and a second cutter free from the first cutter andspring-actuatedly mounted in the body to move longitudinally withrespect to said body and first cutter and positively guided in anarcuate path, said cuttersexpanding during an-upward movement of said"second cutter. 4 i v 20. An underreamer having. a body, alongitudinally immovable cutter supported in the body to tilttransversely and project- 1 ing from the lower end thereof, and a secondcutter having means for positively cutter longitudinally slidable in thelower end .Of the body in an arcuate path and in respect 'to the firstcutter, and means for automatically elevating the second "cutterscausing said cutters'to expand, said cutters having cooperating inthrustbearing surfaces abutting against each; other below the body when thecutters are in expanded position.

22. An underreamer having a body pro- I vided withopen slip-ways toreceive reaming cutters, a cutter in one slip-way supported tov tilttransversely, a second cutter longi tudinally slidable in theother-slipeway in 3 respect to the first critter and'in an arcuate path,and automatic means for elevating the second cutter to expand bothcutters, the cutters having body portions and shank por-.

tions, said body portions with co-operating inthrust'bearing surfaceextending laterally beyond the shanks. 1

23. An underreamer havinga body, a cutter tiltingly-supported by thebody, a second cutter longitudinally slidable in 'the body downwardlywith an arcuate path and in respect to the'first'cutter, and means forauto--' matically elevating the second cutter to exabutting against eachother when are in expandedposltion. v

pan d thecutters, said cuttershaving cooperating arcuate inthrustbearingsurfaces the cutters 24.. An underreamer having a body provided withopen slip-ways to receive reamported totilt transversely, a secondcutter longitudinally slidable in the otherslip-way in an arcuate pathand in respect to the first cutter, and automatic means for elevatingthe second cutter to expand both cutters, the cutters having cooperatingarcuate'im thrust bearing surfaces abutting against each other when'thecutters are in expanded position, and withthe arcuate int-hrust bear-.ing surfaces being of. a curvature.-corre sponding to the arcuate ofthe second cut-ter. a V r 25. An underreamer having a body, alongitudinally-immovable cutter supported in thebody totilt transverselyand projecting below the-lower end of thebody, a second cutterprojecting below the lower end of the body and positively guided toslide longitudinally in the body in an arcuate path and in respect tothe first cutter, and means for path of movement ,ing cutters, acutterin one slip-way supautomatically elevating the second cutter tovided with up-thrust bearing surfaces for abuthientgwith thelower end ofthe' body,

when said cutters are expanded.

26. An 'underreamer havinguav body provided' with open slip-ways 'toreceive reaming. cutters and having up-thrust bearing surfaces onopposite sides of the slip-ways, a

' longitudinallyimmovablecutter in one slip Way supported to tilttransversely, a secondcut-ter longitudinally slidablein the otherslip.-way with. means for positively guiding the same to move'in anarcuate pathjand expand both cutters, the cutters being promeans forelevating said. second cutter to cause the cutters to expand, saidcutters having up-thrust bearing surfaces for contactingsaid up-thrustbearing surfacesof the body when the cutters. are expanded."

27. An underreamer having a body provided with open slip-waysto receivereaming cutters. and having its under surface on opposite side s'of theslip-ways-formedito provide "opposite rip-thrust bearing surfaces angledlnwardly and upwardly, alongitudu nally-immovable cutter in one slip-waysupported to tilt transverselyya second cutter longitudinally slidablein the otherslips-way withmeansfor positively guiding the same to movein an arcuate path, and means for elevating said second cutter to causethe cutters .to expand, the cutters havingshanks extending upwardly intotheslip-ways and provided with inwardly andupwardly an- 7 gledLip-thrust bearing surfaces'for cooperat on with'the up-thrust bearligsurfaces of the body when in expanded position.

" 28. An underreamer having a body pro-"1 able cutter in the'opposed'slipway, the cut vidingja first slip way defining straight outthrustbearingsurfaces and an-opposedslip-r w'ay defining arcua-te out-thrustbearing surfaces, a longitudinally immovable tilting cutter in the firstslip-way,'a longitudinally slid- 'ters-havingout-thrust bearing surfacesfor the out-thrust bearing surfaces of :from the lower surfaceoffthe-b'ody and defining out-thrust bearing surfaces aPcutter theirrespective slipqva'ys arid'inner surfaces- 10, cooperatingtoexpandthecutters upon an elevation of the slidable cutter, the! upperp'ortions ofsaid inner surfaces having an arcuate curvaturecorresponding tothat of r the arcuate out-thrust bearing surfaces ofl5t'he sli'dable cutter, whereb'y'upon an initial downward 'nioveinent or;the sliding cutter an initial collapsing of the cutters is effectedwhile maintaining afullengagement of the cooperating out-thrust bearingsurfaces. 29; An underreamer including a'bodyl1avingaside opening springchamber, a cutter longitudinally sli'dable in the body below "saidchamber, "'a' clo'sure for said'cha'mber, a rod'and actuatingspringcarrled bysaid clo- -ZS sure," and1neans= connect1ng the" rod with saidcutter. p

30." An und'erreamer includinga'body havl'ng a sidebpenmg spring chambera cutter longitudinally, slidable in the body below -means to permitharemoval of the closure,

' l saidchamber,'ai'cl osure for saidv chamber, a

spring actuated rod carried by said-"closure,

a spring eXert-ing an upwardpull"onqthe rod, "means connectlng therod'with saidcutter, and independent means fo-r' rehe'vmg' saidvconnectin'g-Mmeans of the tension of the spr ng for akhsconnectionofSlZLIdCOl'IIIQCtIIIg spring rod'and'springas aunit.

31. An und'erreainer including a body havi in on aosed 0 Jen sli J-wavsto receive ream-' 11 mg cuttersya'nd aninternrediate web, a cutter inone slip-wayand' having a projection? en a in f'said web for tiltin l suaoruin i n t: o b b said "cutter; said 'proj ection' extending intohavinga-straight shank extending into the straight slip-way andsupported on the body totilt transversely, a second cutter} having anarcuate shank longitudinally slidable in the arcuate slip-way, andautomatic liieans V for translating the second cutteigthe inner "Wallsorthe cutters havingco-engaglnglatch.

' shoulders and expanding 'surfaces c ausi'nga tail ways and theotherof; said slip-Ways iaving undercut sidewalls defining ar'cuate'dove-tail ways, a cutter having a shank in theo'pposed slip-way g'asecond cutter longie I tudinally slidable the-opposed slip-way'andlmving camslioulder adapted upon "*Yjdow'nward movement of thesliding -cutter,-

to engage the projection Yon the tilting-cutter and positively move itto collapsed position."

An underre'ainer including a: body hava straight slipi-Way andan'opposed' arcur'ate'slip-way, each extending upwardly froin" f thelower surface of the bod a cutter have f ing a straight shank extending"into the" straight slip way andsup-ported on th'ebody to tilt'transversely a second'cutter' having 'w.-'a1'1*arcuate shanklongitudinally sllidable in 5 the 'arcuate slip-way; and automatic means"for translating the second cutter'to' cause anexpanding co-engagementof both cutters.

33. An:- underreamer including a *body having astraightsli" -Way;andanopposed. aremate 'siip wayyeaerest riding "upwardly" the straightslip-way, provided with straight including a body having opposed open-slip-ways extending 'upwardly from its lower surfacejone oi'said'slip-ways being straight andf' -having undercut side-wallsdefining straight dovedove-tail "ribs engaging withinthe straight.

dove-tail ways. and supported on the body to tilt transversely, a secondcutter having a shank longitudinally shdahle. in said other slip-way andprovidedwith arcuate dovetail ribsengaging Within the 'arcua'te dovetailWays, and automatic im'eans'for actuating the second cutter tocau'se anexpansion ofboth cutters.

35. An underreamer including "a body having opposed 0 en slip-waysextending upwardlyirom its, ower surface,'said lower surface 'on'op'positesides of theslip-Ways -(:lefining opposed rip-thrust bearingsurfaces angled upwardly and inwardly towards each other, oneof'jsaid'slip ways havingFundercut SlQlQ-jWfiliS Clefil'llllg Stf'fllghtdove-tail Ways angled upwardly and 'out ivrardly and theother ofsaidslip-ways having undercut side walls defining arc ua'te dove-tailways, a cutter having a shankin-said one slip-way provided with straightdove-tail ribs engaging, within the straight dove-tail ways and"supported on lthebody to, tilt transversely, acsecond cutter having ashank" longitudinally slidable in said other slipway and provided witharcuate dovetail ribs engaging within the arcuate dove-tail ways,'a ndautomatic means foractuating the .llO

second cutter to cause an expansion offboth- Cutters, the cutters havingup-thru'st bear ing surfaces engaging'the upthrustbearing surfacesof'the bodyfwheuthe j'cutters are expanded, and cooperatingarcuate'inthrust bearing surfaces of a curvature'corre spending to. thatof the arcuate'ways' and oirth e slilable cntten- 36. An underreamerbody having two opposed longitudinally disposed slip-ways extendingupwardly from its lower surface, one slip-way defining straightout-thrust bearing surfaces and the other defining arcuate out-thrustbearing surfaces of uniform curvature, a cutter in one slip-way, and acutter in the other slip-way, said cut ters having faces which abutagainst each other and co-operate to hold the cutters expanded.

37. An underreamer body having two opposed longitudinally disposed openslipways extending upwardly from; its lower surface and an intermediatecutter-supporting web, one slip-way defining straight outthrust bearingsurfaces and the other defining uniformly curved arcuate out-thrustbearing surfaces, a cutter guided to slide on the said arcuate bearingsurfaces and a cutter co-operating with the same and mounted in theother slipway.

38. In an underreamer the combination of a body, a cutter'mounted on oneside of said body with means for holding the same against longitudinalmovement in the body, a second cutter mounted on the other side of saidbody, said second cutter having means for positively guiding the same inan arc extending downwardly in the body and operating to permit thesecond cutter to move downwardly with respect to the other cutter andinwardly toward the axis of the body, while the first named cutter ismaintained against longitudinal movement in the body.

39. In an underreamer the combination of a body having a straightdove-tailed slipway providing out-thrust bearing surfaces, and having anarcuate dove-tailed slip-way on its opposite side providing out-thrustbearing surfaces, a cutter in each of said slipways and co-operatingsoas to have.

transverse collapsible movement, and capable of an expanding movementwith both said cutters in engagement with their outthrust bearingsurfaces.

40. An underreamer including a body having a side opening spring chambera cutter longitudinally slidable in the body below said chamber, aclosure for said chamber, a spring actuated rod carried by said closure,and means including a pivot connection connecting the rod with saidoutter.

Signed at LOs Angeles, California, this 23d day of September 1922.

WILLIAM E. YOULE

